Steam Injection Dual Fuel Nozzle Design And Numerical Simulation Of Combustion Flow Filed

CRGT(Chemically Recuperated Gas Turbine)can recover a part of residual heat of the exhaust gas, which is used to increase the output power of gas turbine and the thermal efficiency and decrease the amount of NOx emissions. CRGT not only can use reforming gas or oil as fuel in the combustion chamber, but also can use mixed combustion of two kinds of fuel. In the chemical regenerative cycle process, steam injection is indispensable,which may cause flameout in the combustion chamber.This paper takes a certain type of gas turbine combustion chamber as the foundation,created calculation model of combustion chamber geometry of CRGT, and simplified the geometric model. The Fluent software is used to simulate the flow field of the combustor:using realizable k-? turbulence model, PDF combustion model and EDC model. The standard wall function was used to deal with the wall. The pollutant production model was used to simulate NOx emissions.First, the PDF model is used to simulate the cold field. The simplified combustor model is simulated by EDC model. The various data of various mass fraction distributions,temperature distribution, velocity field distribution that indicating combustion interior flow field in combustor are obtained. The reasons of flameout in the combustor are analyzed according to the simulation results. The influences of jet diameter and jet velocity on the jet penetration depth are simulated to obtain the corresponding formula.The improvement on the dual fuel nozzle steam nozzle is according to the simulation results. High temperature area,the recirculation zone,steam flow rate and the water steam injection flow when flameout and other important data in combustor are analyzed to investigate the feasibility and benefits of the nozzles. The final design nozzle structure could increase the steam injection rate from 0.25kg/s to 0.6kg/s. Then nozzle installation position is optimized. The improved nozzle is compared with the prototype laboratory.The simulation results show that the improved nozzle decreased NOx emissions. When steam injection flow increases, the uniformity of the temperature at the outlet decreases.The NOx emission of the combustor o is reduced to 1ppm.